/**
 * Copyright (c) 2009 Sergiy Kovalchuk (serg472@gmail.com)
 *
 * Dual licensed under the MIT (http://www.opensource.org/licenses/mit-license.php)
 * and GPL (http://www.opensource.org/licenses/gpl-license.php) licenses.
 *
 * Following code is based on Element.mask() implementation from ExtJS framework (http://extjs.com/)
 *
 */
;(function ($) {

    /**
     * Displays loading mask over selected element(s). Accepts both single and multiple selectors.
     *
     * @param label Text message that will be displayed on top of the mask besides a spinner (optional).
     *                If not provided only mask will be displayed without a label or a spinner.
     * @param delay Delay in milliseconds before element is masked (optional). If unmask() is called
     *              before the delay times out, no mask is displayed. This can be used to prevent unnecessary
     *              mask display for quick processes.
     */
    $.fn.mask = function (label, delay) {
        $(this).each(function () {
            if (delay !== undefined && delay > 0) {
                var element = $(this);
                element.data("_mask_timeout", setTimeout(function () {
                    $.maskElement(element, label)
                }, delay));
            } else {
                $.maskElement($(this), label);
            }
        });
    };

    /**
     * Removes mask from the element(s). Accepts both single and multiple selectors.
     */
    $.fn.unmask = function () {
        $(this).each(function () {
            $.unmaskElement($(this));
        });
    };

    /**
     * Checks if a single element is masked. Returns false if mask is delayed or not displayed.
     */
    $.fn.isMasked = function () {
        return this.hasClass("masked");
    };

    $.maskElement = function (element, label) {

        //if this element has delayed mask scheduled then remove it and display the new one
        if (element.data("_mask_timeout") !== undefined) {
            clearTimeout(element.data("_mask_timeout"));
            element.removeData("_mask_timeout");
        }

        if (element.isMasked()) {
            $.unmaskElement(element);
        }

        if (element.css("position") == "static") {
            element.addClass("masked-relative");
        }

        element.addClass("masked");

        var maskDiv = $('<div class="loadmask"></div>');

        //auto height fix for IE
        if (navigator.userAgent.toLowerCase().indexOf("msie") > -1) {
            maskDiv.height(element.height() + parseInt(element.css("padding-top")) + parseInt(element.css("padding-bottom")));
            maskDiv.width(element.width() + parseInt(element.css("padding-left")) + parseInt(element.css("padding-right")));
        }

        //fix for z-index bug with selects in IE6
        if (navigator.userAgent.toLowerCase().indexOf("msie 6") > -1) {
            element.find("select").addClass("masked-hidden");
        }

        element.append(maskDiv);

        if (label !== undefined) {
            var maskMsgDiv = $('<div class="loadmask-msg" style="display:none;"></div>');
            maskMsgDiv.append('<div>' + label + '</div>');
            element.append(maskMsgDiv);

            //calculate center position
            //maskMsgDiv.css("top", Math.round(element.height() / 2 - (maskMsgDiv.height() - parseInt(maskMsgDiv.css("padding-top")) - parseInt(maskMsgDiv.css("padding-bottom"))) / 2)+"px");
            maskMsgDiv.css("left", Math.round(element.width() / 2 - (maskMsgDiv.width() - parseInt(maskMsgDiv.css("padding-left")) - parseInt(maskMsgDiv.css("padding-right"))) / 2) + "px");
            var top = $(window).height() / 2 - 100;
            var scrollTop = $(document).scrollTop();

            if (element.height() < (top + scrollTop)) {//如果需要遮罩的div的高度小于屏幕中间位置的高度，取div自己的高度
                maskMsgDiv.css("top", Math.round(element.height() / 2 - (maskMsgDiv.height() - parseInt(maskMsgDiv.css("padding-top")) - parseInt(maskMsgDiv.css("padding-bottom"))) / 2) + "px");
            } else {//否则去屏幕中间位置的高度
                maskMsgDiv.css("top", top + scrollTop + "px");
            }

            // 始终在屏幕正中间位置
            /*var top = $(window).height()/2 - 50; 
            var left = $(window).width()/2; 
            var scrollTop = $(document).scrollTop(); 
            var scrollLeft = $(document).scrollLeft();
            maskMsgDiv.css( { position : 'absolute', 'top' : top + scrollTop, 'left' : left + scrollLeft } );*/

            maskMsgDiv.show();
        }

    };

    $.unmaskElement = function (element) {
        //if this element has delayed mask scheduled then remove it
        if (element.data("_mask_timeout") !== undefined) {
            clearTimeout(element.data("_mask_timeout"));
            element.removeData("_mask_timeout");
        }

        element.find(".loadmask-msg,.loadmask").remove();
        element.removeClass("masked");
        element.removeClass("masked-relative");
        element.find("select").removeClass("masked-hidden");
    };

})(jQuery);